By Brian Ellsworth and Andrew Cawthorne
CARACAS (Reuters) - Venezuelans voted for a new legislature on Sunday in an election that may punish the ruling Socialists for a brutal economic crisis and give the opposition a long-sought platform to challenge President Nicolas Maduro.
Chronic product shortages and the world's highest inflation could hand "Chavismo" a first loss in the National Assembly since the movement's charismatic late founder, Hugo Chavez, took office in 1999, polls show.
Winning a majority of the 167 seats would not give the opposition power to overhaul the dysfunctional state-led economy. But it would shatter the Socialist Party's aura of invincibility and may embolden foes to seek a recall of Maduro in 2016.
It would also deal another blow to Latin America's left after Argentina swung to the right in last month's presidential election.
"Our time has arrived," said Diana Rodriguez, 37, a teacher and mother-of-two voting in affluent east Caracas, dressed in white in solidarity with imprisoned opposition leader Leopoldo Lopez and other activists in jail.
"This country is no longer 'Chavista'. Chavez died and no-one can stand the man who's replaced him."
A former bus driver and foreign minister, Maduro, 53, voted in the same poor neighborhood that his mentor and predecessor used to, on a hill overlooking the presidential palace.
Flanked by family and red-shirted party militants, Maduro promised that the government's priority, should it re-take the assembly, would be to tackle Venezuela's economic problems and defeat the "parasitic bourgeoisie."
After government supporters woke voters up with horns and fireworks before dawn, long queues formed at voting centers around the nation, guarded by 163,000 soldiers.
Videos circulating online appeared to show five prominent socialist politicians being booed at voting centers, with crowds yelling "the government will fall!" or "thief!".
In the first major controversy of the day, the National Electoral Council, which critics accuse of a government bias, said it was suspending the observation credentials of former Bolivian president Jorge Quiroga for criticisms he has made.
Quiroga, a conservative who is in Venezuela to support the opposition, said jailed politicians should be allowed to vote and criticized state media for skewed coverage.
Slamming the move as "abusive," the opposition said former Colombian President Andres Pastrana and former Uruguayan President Luis Lacalle had also seen the suspension of their formal authorization to observe the election.
"They are clowns ... they should be expelled," Venezuela's powerful National Assembly president and Socialist Party No. 2 Diosdado Cabello told reporters.
In further controversy, the National Election Council extended voting for an hour until 7 p.m. local time (1830 EST). The opposition said that move was illegal and a sign of desperation.
"The electoral law has been violated," opposition coalition head Jesus Torrealba told reporters, saying protests were being sent to foreign bodies including the United Nations.
Though the opposition is confident of victory, the government counts on a hard core of supporters still devoted to Chavez's memory and scared the opposition will dismantle popular welfare programs such as subsidized food.
"Chavismo deserves to win to continue the legacy of our commander, so everything he's done for us isn't in vain," said Carmen Serrano, 23, from the late leader's plains hometown of Sabaneta.
The Socialist Party benefits from a geographic distribution of seats that favors historically pro-government rural areas over cities. That could mean the overall vote will not be precisely reflected in the number of seats won by each side.
The practical impact of a potential opposition victory would depend on how large a majority it wins.
Taking two thirds of the seats would allow Maduro's adversaries to sack cabinet ministers as well as name directors of the National Electoral Council.
With a simple majority, lawmakers could pass an amnesty law to seek the release of jailed politicians such as Lopez, who was arrested for leading 2014 anti-government protests.
They could also open investigations of state agencies, interrogate cabinet ministers and pressure for the publication of economic indicators such as inflation that have been kept under wraps as the economy has unraveled.
Last year's collapse in oil markets has left the OPEC member struggling to pay its bills, while rigid currency and price control systems have spurred shortages.
The election will have no immediate impact on Maduro's term in office, which expires at the start of 2019.
But the opposition can seek a recall referendum next year by collecting about 4 million signatures.
"According to what we know, the situation is not exactly good for the government," said opposition politician Henrique Capriles, who narrowly lost a 2013 presidential election against Maduro, after voting.
(Additional reporting by Eyanir Chinea, Corina Pons, Alexandra Ulmer, Girish Gupta, Diego Ore and Deisy Buitrago in Caracas, German Dam in Puerto Ordaz and Mircely Guanipa in Punto Fijo; Editing by Mary Milliken, Richard Balmforth and Andrew Hay)